Micropropagation Effects on Juvenile Traits, Flower Differentiation, and Tree Architecture in Young Olive Trees

Abstract

Olive micropropagation is nowadays possible but knowing if it induces juvenile traits and how juvenility, vigor and fruit productivity are affected is pivotal. Three trials were carried out during micropropagation and afterwards in the field. Three varieties were characterized during multiplication in vitro, after several subcultures. ‘Arbequina’ revealed higher shoot miniaturization than ‘Coratina’ and ‘Frantoio’, and likely-juvenile shoots with three or four leaves per node. The ‘Arbequina’ trees obtained from two- and three-leaves-per-node in vitro plantlets were compared to cuttings in the field. Two years after planting, flower-differentiated shoots were found in the apical part of the canopy in all tested trees while in this position the ramification was more intense on three-leaves-per-node trees. Architecture of ‘Arbequina’ trees from micropropagation and cuttings was finally characterized in a high-density commercial grove. Micropropagated trees showed a well distributed and deep root system, a regular conical shape of the canopy, a higher number of primary branches, and a reproductive ability equivalent to cuttings. In conclusion, some juvenile traits and vigor may appear in vitro and last after ex vitro acclimation, but no more than two years in the field.

Keywords

• cutting
• in vitro propagation
• juvenility
• <i>Olea europaea</i> L.
• vigor